PK Study of IV Formulation of GW856553

Inclusion Criteria: * AST, ALT, alkaline phosphatase and bilirubin ≤ 1.5xULN (isolated bilirubin \>1.5xULN is acceptable if bilirubin is fractionated and direct bilirubin \<35%). * Healthy as determined by a responsible and experienced physician, based on a medical evaluation including medical history, physical examination, laboratory tests and cardiac monitoring. * Male or female between 18 and 75 years of age inclusive, at the time of signing the informed consent. * A female subject is eligible to participate if she is of non-childbearing potential defined as pre-menopausal females with a documented tubal ligation or hysterectomy; or postmenopausal defined as 12 months of spontaneous amenorrhoea * Male subjects must agree to use contraception from the time of the first dose of study medication until seven days following the last dose. * Body weight \>50kg (110 pounds) and body mass index (BMI) within the range \>19 and \<30kg/m2. * Capable of giving written informed consent, which includes compliance with the requirements and restrictions listed in the consent form. * QTcB or QTcF \< 450 msec. Exclusion Criteria: * A positive pre-study Hepatitis B surface antigen or positive Hepatitis C antibody result within 3 months of screening * Current or chronic history of liver disease, or known hepatic or biliary abnormalities (with the exception of Gilbert's syndrome or asymptomatic gallstones). * A positive pre-study drug/alcohol screen. * A positive test for HIV antibody. * History of regular alcohol consumption within 6 months of the study defined as an average weekly intake of \>21 units for males or \>14 units for females. One unit is equivalent to 8g of alcohol: a half-pint (\~240 ml) of beer, 1 glass (125ml) of wine or 1 (25ml) measure of spirits. * Treatment with an investigational product within 90 days or 5 half-lives or twice the duration of the biological effect of the investigational product (whichever is longer) prior to dosing in this study. * Exposure to more than four new chemical entities within 12 months prior to the first dosing day. * Where participation in the study would result in donation of blood or blood products in excess of 500mL within a 56 day period. * Pregnant females as determined by positive serum or urine hCG test at screening or prior to dosing. * Lactating females. * Unwillingness or inability to follow the procedures outlined in the protocol. * Subject is mentally or legally incapacitated. * Taking prescription or non-prescription drugs (including vitamins and dietary or herbal supplements), within 7 days (or 14 days if the drug is a potential enzyme inducer) or 5 half-lives (whichever is longer) prior to the first dose of study medication until completion of the follow-up visit, unless in the opinion of the Investigator and Sponsor the medication will not interfere with the study.